This invention relates to a simple regulator for controlling pressures at extremely low pressures. More particularly it relates to a low pressure regulator that regulates pressure by use of a recycle bore on the outlet side. The recycle bore allows the outlet pressure to exert a force on a plunger top having a larger surface area, while the inlet pressure exerts a force on a significantly smaller surface area of the plunger.
U.S. Pat. No. 4,276,902 discloses a rigid plastic valve housing having opposed inlet port and outlet port and a hollow cylindrical interior having four stepped concentric cylindrical bores. The sealing means are O-rings and the first actuating means is on the solid flat piston head and the second actuating means is a compression loaded metal spring.
U.S. Pat. No. 3,374,803 discloses a valve which maintains a set pressure for operating a device and is actuated by at least one spring and U.S. Pat. No. 3,269,598 discloses a pressure regulator for use in supplying gas pressure to a dispenser for a liquid. The valve is spring activated and is normally in the open position.
U.S. Pat. No. 2,660,834 discloses a pressure regulator where the inlet port is below the outlet port and the sealing means is positioned in between the inlet port and the outlet port in the closed position.
The above disclosed references incorporate springs and do so principally in order to actuate the piston to counteract the effect of the pressure from the inlet port. This invention does not require a spring for operation of the valve.
It would be desirable to have a simple pressure regulator for controlling pressures at extremely low pressures. High pressure is defined for purposes of this specification to be greater that 100 psig and low pressures are defined as those below 100 psig and extremely low pressures defined those between 0 and 10 psig. While the need for a pressure regulator to control pressures below 100 psig is desirable, there is an especially significant need to control pressures between 0 and 10 psig.
Carbon dioxide and nitrogen are used as propellants to dispense food beverages. Generally the food beverage is dispensed from commercial containers using these gases in pressures of 10 to 40 psig. Pressures below 10 psig are desirable to minimize foaming of the product, as in the case of beer. A low pressure inline regulator would eliminate the need for calculating and using excess dispensing hoses, tubing or piping to accomplish the required pressure drop to obtain extremely low dispensing pressures below 10 psig.
Certain common and widely used laboratory test methods use inert gases to purge or blanket test apparatus for safety purposes and to assure noncontamination of materials tested. Gases such as nitrogen and argon are generally used for such purposes. Extremely low gas pressure of less than 10 psig are preferred in such an apparatus, because the apparatus is generally glass and the possibility of breakage is minimized. Low pressure gas control is currently accomplished in such an apparatus by using an external pinch valve on flexible tubing or hosing or an insertion of a physical restriction in the gas supply line. Both the above controls are potentially dangerous to the apparatus in the event that either the pinched valve or other restriction works loose and sufficiently high pressures develop. This can result in the breakage of apparatus and loss of test results and possible injury to personnel.